Method for measuring the thickness and/or length of objects and devices for this purpose

ABSTRACT

The invention relates to a method and to devices for measuring the thickness and/or length of objects ( 12 ) such as tablets, making use of a magnetic length-measuring system comprising a magnetic belt ( 5, 15 ) provided with pole pitches and with a magnetic field sensor ( 6, 20 ) located across from the magnetic belt ( 5, 15 ), having an electric evaluation circuit and having a placement surface ( 25 ) for the object ( 12 ) to be measured. The magnetic field sensor ( 6, 20 ) is mounted so as to be stationary while the magnetic belt ( 5, 15 ) is moved lengthwise past the magnetic field sensor ( 6, 20 ). A projecting arm ( 10, 21 ) is connected to the magnetic belt ( 5, 15 ) for purposes of making contact with the object to be measured, said arm accompanying the movement of the magnetic belt ( 5, 15 ), whereby the direction of movement of the magnetic belt ( 5, 15 ) is either parallel to the normal of the placement surface ( 25 ) or else it runs perpendicular thereto.

The invention relates to a method for measuring the thickness and/orlength of objects having a solid or gel-like consistency, especiallypharmaceutical objects such as tablets, pills or oblongs, making use ofa magnetic length-measuring system comprising a magnetic belt providedwith a plurality of pole pitches and with a magnetic field sensorlocated across from the magnetic belt, whereby the magnetic field sensorand the magnetic belt run lengthwise parallel to each other, having anelectric evaluation circuit connected to the magnetic field sensor forpurposes of evaluating the pulses supplied by the magnetic field sensor,and having a placement surface for the placement of the object to bemeasured. The invention also relates to devices for measuring thethickness and/or length of objects having a solid or gel-likeconsistency, especially pharmaceutical objects such as tablets, pills oroblongs.

Magnetic length-measuring systems are known that work by means of amagnetic belt with a pole pitch and with a magnetic field sensor that ismounted across from the magnetic belt. Here, the magnetic belt isstationary and the magnetic field sensor is contact-free and thuslargely free of wear and impervious to dirt. The magnetic field sensorrequires a cable to convey the electric pulses whereby, when themagnetic field sensor moves, the cable has to be dragged along and thushas to be suitable for a drag chain, which entails more complex materialand higher costs. When the pole pitches of the magnetic belt pass themagnetic field sensor, the latter emits electric signals that are sentto an electronic evaluation circuit and counted. The electric signals ofthe magnetic field sensor obtained on the basis of the pole pitch of themagnetic belt are counted in the electronic evaluation circuit andtransformed into a length measurement that corresponds to the polepitch.

The company Fritz Kübler GmbH, www.kuebler.com, publication numberR1002250310003ES, located in 78054 Villingen-Schwenningen, Germany hasmade such a linear measuring system consisting of a movable magneticsensor and a stationary magnetic measuring belt at a pole distance of 2mm from pole to pole, resulting in a periodical index signal every 2 mmas counting pulses. The magnetic sensor attains a resolution of 0.025 mmwith a four-fold evaluation or of 0.05 mm to 0.1 mm. Thus, thesuccession of two adjacent counting pulses constitutes the traversing ofa pre-specified path of the magnetic sensor that is determined by itsresolution.

In the pharmaceutical industry, during the production of pharmaceuticalobjects such as tablets, pills or oblongs, various parameters of theobjects, such as the weight, the bursting strength or the thickness orlength, have to be checked and measured, often continuously. Themeasuring devices used so far for measuring the thickness or length oftablets, pills or oblongs either work too slowly or too imprecisely, orelse both.

The invention is based on the objective of using a magneticlength-measuring system in a method of the above-mentioned type as wellas in a device for measuring the thickness of objects having a solid orgel-like consistency, especially pharmaceutical objects such as tablets,pills or oblongs, thus rendering said method usable in said device.

The objective is achieved with a method of the above-mentioned type inthat the magnetic field sensor is mounted so as to be stationary whilethe magnetic belt is moved lengthwise past the magnetic field sensor anda projecting arm is connected to the magnetic belt for purposes ofmaking contact with the object to be measured, said arm accompanying themovement of the magnetic belt, whereby the direction of movement of themagnetic belt is either parallel to the normal of the placement surfaceof the object to be measured or else it runs perpendicular thereto.

The objective is also achieved by a device for measuring the thicknessand/or the length of objects having a solid or gel-like consistency,especially pharmaceutical objects such as tablets, pills or oblongs,said device comprising a base from which a column rises vertically, andeither the base or the column or both have a placement surface for theobject to be measured, whereby a magnetic length-measuring system isarranged along the column and it comprises a magnetic belt provided witha plurality of pole pitches and with a stationary mounted magnetic fieldsensor located across from the magnetic belt as well as an electricalevaluation circuit connected to the magnetic field sensor, whereby themagnetic belt is mounted so that it can be moved along the column pastthe magnetic field sensor by means of a motor, while a projecting armengages the magnetic belt, said arm being able to accompany the movementof the magnetic belt for purposes of making contact with the object tobe measured.

The method and the device according to the invention have theoutstanding advantage that, since the magnetic field sensor is mountedso as to be stationary while the magnetic belt is arranged so as to bemovable up and down or back and forth, there is no movable cableconfiguration for the magnetic field sensor but rather only a mechanicalmovement of the magnetic belt. There is no longer a need for the cableto be suitable for a drag chain. Such an embodiment, namely, that themagnetic belt moves while the magnetic field sensor remains stationary,is best suited for the measurement of short distances, whereby thethickness measurement of such objects of the type generally encounteredwith pharmaceutical objects such as tablets, pills or oblongs, involvesshort distances to be measured. The magnetic length-measuring systemhere is a translatorily functioning length-measuring system.

In another embodiment of the invention, the magnetic belt is mounted ona carriage that is secured on or in the column so as to be translatorilymovable lengthwise. If the magnetic belt is located inside the column,then a groove can be arranged in said column in which the carriage issecured so as to be movable up and down or back and forth.

Furthermore, the carriage can have a means that serves to move it,whereby an electric motor acts upon the device so as to move thecarriage and thus the magnetic belt.

The means for moving the carriage can have teeth arranged on the side ofthe carriage into which a drive cog wheel meshes that can be driven bythe electric motor. In an advantageous manner, when the projecting armis lowered in the direction of the object to be measured, the drive cogwheel is disengaged from the teeth of the carriage so that the carriagemoves down towards the object by virtue of the force of gravity.

Furthermore, a spring can engage with the carriage and its spring forcestrives to move the carriage towards the base into a resting position.In an advantageous manner, the spring is a tension spring that engages,on the one hand, with the end of the carriage facing the base and, onthe other hand, with the base. This embodiment is especiallyadvantageous if the device is to serve for length measurement and isconsequently used in such a manner that the base extends verticallyupwards while the column extends horizontally. Here, the placementsurface for the object is situated on the column, and in this case, thenormal of the placement surface of the object is perpendicular to thedirection of movement of the carriage. The spring serves to pull thecarriage with a defined return force in order to touch the object.

In another embodiment of the invention, the magnetic belt is a flexibleloop or else it is flexible and mounted on a loop, and runs over tworollers, one of which, preferably the drive roller, is located in thearea of the base while the other is arranged at the opposite end of thecolumn. Or else the magnetic belt is arranged on a belt that is shapedinto a continuous loop, whereby the belt runs over two rollers, one ofwhich is located in the area of the base while the other is arranged atthe opposite end of the column.

The objective of the invention is also achieved by a device formeasuring the thickness and/or length of objects having a solid orgel-like consistency, especially pharmaceutical objects such as tablets,pills or oblongs, whereby the device consists of a base having aplacement surface for the object to be measured, from which base acolumn rises vertically on which a magnetic length-measuring system isarranged, comprising a magnetic disk provided with a plurality of polepitches and with a magnetic field sensor that is mounted across from themagnetic disk so as to be stationary, having an electric evaluationcircuit connected to the magnetic field sensor, whereby the magneticdisk is mounted in or on the column so as to be rotated past themagnetic field sensor by means of the motor, and the rotational movementof the magnetic disk can be converted into a translatory movement bymeans of a linkage, while a projecting arm that serves to make contactwith the object to be measured engages with the linkage, said arm beingcapable of accompanying the translatory movement. Consequently, themagnetic length-measuring system here is a length-measuring system thatfunctions in a rotatory manner.

BRIEF DESCRIPTION OF THE DRAWING IN WHICH THE FOLLOWING IS SHOWN

FIG. 1 a schematic depiction of a device for measuring the thicknessand/or length of objects, whereby this device has a carriage on which amagnetic belt is mounted, and

FIG. 2 a device for measuring the thickness and/or length of objectshaving a magnetic belt that is designed to revolve continuously.

According to FIG. 1, the device for measuring the thickness and/orlength of objects consists of a base 1 that, at its top, has a placementsurface 25 for an object 12 that can be, for example, a tablet, a pillor an oblong. A column 2 rises vertically from the base 1, preferablyperpendicular to the placement surface 25, whereby preferably thelongitudinal axis of the column 2 and the normal of the placementsurface 25 run parallel to each other. A carriage 4 is movably mountedon or in the column 2. Preferably, a lengthwise groove 3 can be milledinto the column 2, the carriage 4 then running in said groove 3. Inorder for the carriage to be driven, it can have teeth 7 in which adrive cog wheel 9 meshes, said drive cog wheel 9 being driven by anelectric motor 8. The rotation of the electric motor is reversible,which is shown by a curved double directional arrow 24, so that when thedrive cog wheel 9 is rotated, the carriage 4 can be moved back and forthwithin the groove 3.

A magnetic belt 5 with a pole pitch is permanently affixed on thecarriage 4 so that, when the carriage 4 moves, the magnetic belt 5follows along. Across from the magnetic belt 5, there is a magneticfield sensor 6 which is mounted so as to be stationary, preferably onthe column 2, so that, when the carriage 4 moves, the magnetic belt 5moves past the magnetic field sensor 6 and the latter detects thismovement. The magnetic field sensor 6 is connected via a cable 27 to anelectric evaluation circuit (not shown here), and this evaluationcircuit can also be integrated into the magnetic field sensor 6.

On the carriage 4, here at the lower end of the carriage 4, there is aprojecting arm 10 that extends horizontally over the placement surface25 of the object 12 and that is attached to the carriage 4 by means ofscrews 11 in such a way that the arm 10 accompanies the movements of thecarriage 4. The arm 10 serves for placing or contacting the object whena thickness measurement is performed. The embodiment of the device ofFIG. 1 in the position shown, namely, with a horizontally arranged baseand vertically arranged column, preferably serves to measure thethickness of preferably pharmaceutical objects.

The evaluation circuit evaluates the counting pulses coming from themagnetic field sensor 6, whose number corresponds to a certain pathtraversed by the carriage 4 and thus by the arm 10, which can then beshown on a display.

Moreover, in an identical or similar embodiment, the device can be usedfor length measurement. In this case, the column 2 forms the base and itis arranged horizontally, the base 1 extending vertically upwards sothat the device of FIG. 1 is rotated clockwise by 90°. Furthermore, inthis case, a tension spring 26 can engage with the end of the carriage 4facing the base 1 and with the base 1, said tension spring 26 strivingto move the carriage 4, together with the projecting arm, towards thebase and into a resting position.

If, for instance, as in the example shown in FIG. 1, the device with thebase is horizontal and consequently the column 2 extends verticallyupwards, then no tension spring or pressure spring is needed since thecarriage 4 strives to move downwards due to the force of gravity.

If, in contrast, the device is being used as a length-measuring deviceand the base 1 is oriented vertically and the column 2 is orientedhorizontally, then another placement surface 25′ can be provided on thecolumn 2 in order to measure the length of an object. Then the normal ofthe placement surface 25′ runs perpendicular to the longitudinal axis ofthe carriage 4 or of the magnetic belt 5, which moves horizontally. Inthis case, it is advantageous to install a tension spring between theend of the carriage 4 facing the base 1 and the base since the tensionspring 26 strives to move the carriage 4 towards the base 1 into aresting position and thus towards the object. Here, for the object, theprojecting arm 10 forms a stop jaw that extends vertically upwards.

For this reason, the device of FIG. 1 can also be rotated clockwise by90° without a need for further manipulations in order to consecutivelydetermine the thickness and length of an object.

FIG. 2 shows another example of a device according to the inventionpreferably for measuring the thickness of an object 12. On a preferablyhorizontally arranged base 13, a column 14 rises perpendicularly andthus preferably vertically to the base 13, whereby the longitudinal axisof the column 14 is oriented parallel to the normal of a placementsurface 25 for the object 12. In the base 13, there is a first or lowerroller 16—mounted on a drive shaft 19—which can be driven by means of anelectric motor 18, while it carries the roller 16 along. At the upperend of the column 14, a second or upper roller 17 is rotatably mounted,whereby a continuous belt 15 is wrapped around the two rollers 16, 17.The belt 15 can either be a magnetic belt provided with pole pitches orelse the belt 15 can be a flexible steel or plastic belt onto which, atleast partially in the lengthwise direction of the belt 15, a magneticbelt with a pole pitch has been applied which is thus translatorilymovable.

Moreover, for the object 12, an arm 21 projects horizontally beyond theplacement surface 25, whereby the arm 21 is attached to the belt 15 bymeans of screws 23. A stationary magnetic field sensor 20 is mountedacross from the magnetic belt 15.

When the lower drive roller 16 is rotated by means of the electric motor18, the magnetic belt 15 runs past the magnetic field sensor 20,carrying along the arm 21, so that, as described above for FIG. 1, themagnetic field sensor supplies electric-magnetic counting pulses that,in turn, can be evaluated and processed in an evaluation circuit, as aresult of which the thickness of the object 12 can be measured. Thedevice shown in FIG. 2 can also be used when it is rotated clockwise by90°, so that in this case, the length of an object can also be measured.

INDUSTRIAL APPLICABILITY

The invention is industrially applicable especially in thepharmaceutical sector for measuring the thickness and/or length oftablets, pills or oblongs. Due to the high precision of the currentlyavailable magnetic length-measuring systems, such pharmaceuticalproducts can be measured very accurately in terms of their thicknessand/or length, whereby the embodiment of the invention with a movablecarriage or with a movable continuous belt, which carries the magneticbelt, allows a very fast measurement procedure.

LIST OF REFERENCE NUMERALS

-   1, 13 base-   2, 14 column-   3 groove-   4 carriage-   5, 15 magnetic belt-   6, 20 magnetic field sensor-   7 teeth-   8, 18 electric motor-   9 drive cog wheel-   10, 21 arm-   11, 23 screws-   12 object-   16, 17 rollers-   19 drive shaft-   22, 24 double directional arrow-   25, 25′ placement surface for the object-   26 tension spring-   27 cable

1. A method for measuring the thickness and/or iength of objects (12)having a solid or gel-like consistency, especially pharmaceuticalobjects such as tablets, pills or oblongs, making use of a magneticlength-measuring system comprising a magnetic belt (5, 15) provided witha plurality of pole pitches and with a magnetic field sensor (6, 20)located across from the magnetic belt (5, 15), whereby the magneticfield sensor (6, 20) and the magnetic belt (5, 15) run lengthwiseparallel to each other, having an electric evaluation circuit connectedto the magnetic field sensor (6, 20) for purposes of evaluating thepulses supplied by the magnetic field sensor (6, 20), and having aplacement surface (25) for the object (12) to be measured, characterizedin that the magnetic field sensor (6, 26) is mounted so as to bestationary while the magnetic belt (5, 15) is moved lengthwise past themagnetic field sensor (6, 20) and a projecting arm (10, 21) is connectedto the magnetic belt (5, 15) for purposes of making contact with theobject to be measured, said arm accompanying the movement of themagnetic belt (5, 15), whereby the direction of movement of the magneticbelt (5, 15) is either parallel to the normal of the placement surface(25) of the object (12) to be measured or else it runs perpendicularthereto.
 2. A device for measuring the thickness and/or the length ofobjects (12) having a solid or gel-like consistency, especiallypharmaceutical objects such as tablets, pills or oblongs, characterizedin that the device comprises a base (1, 13) from which a column (2, 14)rises vertically, and either the base or the column (2, 14) or both havea placement surface (25, 25′) for the object (12) to be measured,whereby a magnetic length-measuring system is arranged along the column(2, 14) and it comprises a magnetic belt. (5, 15) provided with aplurality of pole pitches and with a stationary mounted magnetic fieldsensor located across from the magnetic belt (5, 15) as well as anelectrical evaluation circuit connected to the magnetic field sensor (6,20), whereby the magnetic belt (5, 15) is mounted so that it can bemoved along the column (2, 14) past the magnetic field sensor (6, 20) bymeans of a motor, while a projecting arm (10, 21) engages the magneticbelt (5, 15), said arm being able to accompany the movement of themagnetic belt (5, 15) for purposes of making contact with the object tobe measured.
 3. The device according to claim 2, characterized in thatthe magnetic belt (5) is mounted an a carriage (4) that is secured an orin the column (2) so as to be movable lengthwise.
 4. The deviceaccording to claim 3, characterized in that, inside the column (2),there is a groove (3) in which the carriage (4) is secured so as to bemovable up and down or back and forth.
 5. The device according to claim2, characterized in that, in order for the carriage (4) to be moved, ithas a movement means (7), whereby an electric motor (8) that serves tomove the carriage (4) and thus the magnetic belt (5) is capable ofacting upon the movement means (7).
 6. The device according to claim 5,characterized in that the movement means has teeth (7) arranged an theside of the carriage (4) into which a drive cog wheel (9) meshes thatcan be driven by the electric motor (8).
 7. The device according toclaim 2 characterized in that a spring (26) engages with the carriage(4) and its spring force strives to move the carriage (4) towards thebase (1) into a resting position.
 8. The device according to claim 9,characterized in that the spring (26) is a tension spring that engages,an the one hand, with the end of the carriage (4) facing the base and,an the other hand, with the base (1).
 9. The device according to claim2, characterized in that the magnetic belt (15) is shaped into a loopand runs over two rollers (16, 17), one of which (16) is located in thearea of the base (13) while the other (17) is arranged at the oppositeend of the column (14).
 10. The device according to claim 2,characterized in that the magnetic belt (15) is arranged an a belt thatis shaped into a continuous loop, whereby the belt runs over two rollers(16, 17), one of which (16) is located in the area of the base (13)while the other (17) is arranged at the opposite end of the column (14).11. A device for measuring the thickness and/or length of objects havinga solid or gel-like consistency, especially pharmaceutical objects suchas tablets, pills or oblongs, characterized in that said device consistsof a base having a placement surface for the object to be measured, fromwhich base a column rises vertically an which a magneticlength-measuring system is arranged, comprising a magnetic disk providedwith a plurality of pole pitches and with a magnetic field sensor thatis mounted across from the magnetic disk so as to be stationary, andhaving an electric evaluation circuit connected to the magnetic fieldsensor, whereby the magnetic disk is mounted in or an the column so asto be rotated past the magnetic field sensor by means of the motor, andthe rotational movement of the magnetic disk can be converted into atranslatory movement by means of a linkage, while a projecting arm thatserves to make contact with the object to be measured engages with thelinkage, said arm being capable of accompanying the translatorymovement.